2005.05.20 16:08 "[Tiff] TIFF/EP and TIFF 6.0", by Bob Young

2005.05.20 17:43 "RE: [Tiff] TIFF/EP and TIFF 6.0", by Steve Carlsen

how does the DNG spec address my questions regarding TIFF?

Only in that it, too, has a (non-binding) opinion on the thumbnail image question.